Breech mechanism for automatic firearms



G. WEBB Sept. 29, 1942.

BREECH MECHANISM FOR AUTOMATIC FIREARMS 2 Sheets-Sheet 1 viii/11162 I T l Q Filed Jan. 17, 1940 Patented Sept. 29, 1942 BREECH MECHANISM FOR AUTOMATIC FIREARMS George Webb, Hartford, Conn, assignor to Colts Patent Fire Arms Manufacturing Company, Hartford, Conn., a corporation of Connecticut Application January 17, 1940, Serial No. 314,271

6 Claims.

The present invention is particularly applicable to automatic firearms of the type shown in Patent No. 1,525,065 to John M. Browning and in Patent No. 1,852,057 to Frederick T. Moore and Christian Pfeiffer, but it is not so limited.

One of the objects of the invention is to provide a readily releasable stop for the transversely movable breech block of a firearm of the type referred to. In accordance with the invention the stop can be readily released manually to permit the breech block to be completely removed from the gun when desired.

Another object of the invention is to provide a simple and readily releasable lock for preventing rotative movement of the barrel. The barrel and the barrel extension reciprocate during operation of the gun and the barrel is disconnectible upon rotation, but rotation of the barrel is normally prevented by a detent which moves bodily with the said barrel and barrel extension. In accordance with the invention, this detent can be released to permit rotation of the barrel, such release being effected by means of a manually operable device which is exteriorly accessible and which does not partake of the reciprocating movement referred to. Also in accordance with the invention the detent for holding the barrel is so mounted and controlled that the barrel can be screwed into its fully connected position without manual withdrawal of the detent and can be freely unscrewed after the detent has been withdrawn to permit starting of the unscrewing movement.

In the accompanying drawings I have shown the embodiment of the invention which I now deem preferable, but it will be understood that the drawings are intended for illustrative purposes only and are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

Fig. 1 is a fragmentary side View of a gun embodying the invention, a certain portion being broken away to show interior parts.

Fig. 2 is a fragmentary vertical sectional View taken along the line 2-2 of Fig. 1.

Fig. 3 is a view similar to Fig. 2 but showing barrel extension and associated parts in elevation and showing the breech block stop in its lower inoperative position.

Fig. 4 is a view similar to Fig. 3, but showing the connecting nut for the barrel extension out of its normal position.

Fig. 5 is a fragmentary vertical sectional view .taken along the line 5-5 of Fig. L.

Fig. 6 is an enlarged fragmentary vertical sectional view taken along the line 6-6 of Fig. 1, but omitting some of the parts shown in detail in Figs. 2 and 3.

Fig. '7 is an enlarged fragmentary vertical sectional view taken along the line 1-1 of Fig. 1.

Fig. 8 is an enlarged fragmentary plan view showing the device for moving the barrel locking detent.

Fig. 9 is a fragmentary sectional view taken along the line 9-9 of Fig. 7.

Fig. 10 is a fragmentary horizontal sectional view taken along the line lll|ll of Fig. 7 and showing the barrel in its locked position.

Fig. 11 is a View similar to Fig. 10 but showing the barrel in the position which it occupies just before engagement with the barrel locking detent.

Referring to the drawings, l represents the main casing which comprises spaced side plates I" and l connected near their front ends with a trunnion block 2. At the top of the casing is a feed box 3 and at the rear of the feed box is a trigger 4. These parts need not be described in detail as the invention does not relate to the details of the feed mechanism or of the firing mechanism. At the front and rear of the feed box are cover plates 5 and 6 which connect the side plates l and l The barrel 1 is longitudinally movable in an opening in the trunnion block and. it is detachably connected with a barrel extension 8 which is longitudinally movable in the casing, being guided at the top and at the bottom by inward projecting flanges on the side plates I and l The barrel extension comprises two spaced legs 8 and 8 The barrel and barrel extension move rearward upon recoil and are returned in the forward direction by the recuperator spring 9. This spring acts through the recuperator rod Ii! which is connected at its rear end with a depending lug B on the barrel extension 8, this connection being by means of a nut IE! as shown clearly in Fig.5.

Also longitudinally movable within the casing is a lock frame II, this frame being shown in Fig. 1 in the rearward position, which it occupies at least momentarily after the firing of each shot. Depending from the lock frame H is a yoke 12 to which are connected two transversely spaced tension rods l3, l3. The depending lug 8 of the barrel extension 8 carries a yoke l4 having laterally projecting arms M 14 as shown the lock frame is at least momentarily held in its rearward position as shown in Fig. 1. The bar rel and barrel extension immediately move forward under the influence of the recuperator spring 9, as already stated, and the tubes 15, I 5 move forward at the same time, thus compressing the springs it, IS andtensioning the rods l3; l3. Upon subsequent release of the lock frame, the springs i6, 16 in cooperation with the rods'l'3, 13, move the lock frame forward, this frame with its associated parts serving to push a cartridge into the chamber of the barrel as explained in detail in the aforesaid patents.

A breech block I1 is provided which moves bodily with the barrel extension 8 which is also movable vertically with respect to the barrel extension, being positioned between the legs 8 and 8 and being guided by ribs 8' and 8. The vertical movement of the breech block H is effected by an actuating lever 18 which is carried by the lock frame I I and which is moved about its pivotal connection 18 by means of a cam structure indicated in its entirety by H) and depending from the main casing at the left side thereof. The actuating lever i8 has transversely projecting studs [8 which are adapted to enter a T-slot I l in the breech-block. When out of engagement with the actuating lever, the breech block I! is retained and supported by a stop 2t, shown in Fig. 1.

When the lock frame moves forward from the position shown in Fig. 1, a cartridge is pushed into the chamber of the barrel, asalready stated. At the same time, a stud at l8 on the left side of the actuating lever l8 travels along the cam groove 9 until it reaches the position shown by dot-and-dash line in Fig. 1. In this position the studs Ifl on the actuating lever are about to enter the T-slot H in the breech block. Continued forward movement of the lock frame and of the actuating lever causes the stud 18 to move downward along the cam groove 19 thus rotating the actuating lever in the counterclockwise direction and moving the breech block upward to its breech-closing position where it serves as an abutment for the cartridge.

Upon recoil, the barrel and barrel extension and the lock frame initially move rearward in unison and during such movement a stud at IS on the left side of the actuating lever la engages the cam surface I 9. This engagement of the stud l8 with the cam surface l9 moves the lever I8 in the clockwise direction and the lever in so moving causes downward movement of the breech block. This clockwise movementof the lever l8 carries the stud 18 into the cam groove le and associated parts, start to move forward to:

Continued rearward movement causes the stud 3 to move past the spring-pressed switch Eri until the parts finally reach the position the position shown in Fig. 1, this forward movement separating the breech block I? from the actuating lever It).

Further and more detailed illustration and description of the operating mechanism for the breech block are to be found in the before-mentioned patents, and the foregoing brief description is sufficient .for purposes of disclosing the present invention.

It is highly desirable that the breech block be readily removable from the gun for inspection, cleaning or replacement In order to permit such ready removal, the stop 28 is relatively movable in the direction shown and it is pivotaliy connected at 2% with the yoke M. The stop is normally held in its upper operative position by a manually releasable means such as a springpressed detent 2i. As shown in Fig. 2, the detent 2| is entered in a hole in the stop 26 and a spring 22 tends to hold it in the operative position shown. By means of a knob. 23, the detent may be withdrawn to the position shown in Fig. 3 compressing the spring 22 and permitting the stop 29 to move to its lower inoperative position A as shown in Figs. 1 and 3. This releases .the breech block IT and permits it to drop downward .as shown at B in Fig. 1, continued downward movement taking it entirely out of the gun.

The breech block H can be put in place readily without interference by the stop 26, and after it is in place the stop can be restored to the position shown in Fig. 2 and shown by full lines in Fig. l, the stop thus again retaining the block.

The stop 29 not only retains the breech block, but it also prevents the nut W from turning. The nut is cut away. as shown at Hi", to provide a clearance cavity to accommodate .the lever I18, and it is normally positioned as shown inFigs. 1 and 3; The stop 20 when in its upper position engagesthe lower flat face of the nut to prevent the nut from turning. If the nut is turned from its normal-position while the stop is in its lower position, it is impossible to return the stop to its upper position, this being clear by reference to Figs. 4 and 5. With the stop in the position shown in these figures the detent cannot enter the hole in the stoptohold it in place.

It will be observed that'with the breech block in the position shown in- Fig. 1 theslot H is' properly positioned to receive the studs-18 on the actuating lever it as the 'saidlever moves forward. During firing, the gun is subject to,

some vibration which might take the breech block out of the position'shown in Fig. 1. .During operation, the'gun is not always in the horizontal position .as shown, but it .may be in an inclined, position or .may even be in an inverted position,

Under all possible conditions of use it is essential that the breech block bein the position shown in Fig. l at the moment whenthe forward movement of the lock frameisaboutto effect the entrance of the studs la into the slot' il To prevent movement of the breech block out of the position shown, a suitable means is provided such as the spring-pressed detent 24 shown clearly in Fig. 6. e As shown, this is mounted in an aperture in the left leg 8 of the'barrel extension. The detent 2 3 is pressed into its operative position by means of a spring 25 which abuts against a'plug 28 threaded into the aperture in the barrel extension leg. This detent serves to resist movement of the breech block ll out of its lower-position andthus prevents any movement resulting fromvibrationor resulting from the action of gravity. However, the detent.

24 is cammed out of the way when the breech block is positively moved upward by the actuating lever IS.

The detent 24 while herein fully disclosed, does not of itself constitute any part of the present invention, this being shown and claimed in the co-pending application of Wm. L, Swartz for Breech mechanism for automatic firearm, Serial No. 314,272 filed on even date herewith.

As already stated, the barrel l is detachably connected with the barrel extension 8. The connection between the barrel and the barrel extension is of such character that these parts can be detached by rotary movement of the barrel and I have shown for this purpose a simple threaded connection at El. In order to prevent unintended rotative movement of the barrel 1, barrel locking mechanism is provided which now constitutes the subject matter of divisional application, Serial No. 437,851, filed April 6, 1942, in the name of George Webb. Details of this mechanism comprise a detent 28 which is movably mounted in a longitudinal hole in the barrel extension, as shown in Figs. and 11, this detent being pressed in the forward direction by means of a spring 29, A pin 35 is carried by the detent 28, this pin projecting through a slot 3i in the side of the barrel extension. The pin 36 serves to limit longitudinal movement of the detent 28 and also has another function as will presently appear.

The barrel 1 has a notch 32 for receiving the detent 23 and when the detent is entered in the notch, as shown in Fig. 10, rotation of the barrel is effectively prevented. Preferably, the forward movement of the detent 28 is so limited that its maximum projection forward from the front face of the barrel extension is slightly less than the lead of the thread of the threaded connection at 21. This makes it possible for the barrel to be freely turned and moved into its fully engaged and locked position without, any interference by the detent 28. Fig. 11 shows the barrel partly engaged, one more turn being necessary to cause it to be fully engaged. It will be seen that with the notch 32 in register with the detent 28, the detent does not project far enough to enter the notch and therefore does not interfere with continued rotation of the barrel in the engaging direction. Only when the barrel reaches its fully engaged position, as shown in Fig. 10, does the detent enter the notch and prevent rotation of the barrel.

It will be understood from the prior description that the barrel and barrel extension move rearward from the position shown in Fig, 10 during each functoning of the gun. In accordance with the invention, I provide a manually operable means for releasing the detent 28, this means being so constructed that it does not partake of the bodily movement of the barrel and barrel extension but nevertheless serves to relatively move the detent 28 when the barrel and barrel extension are formed. As shown, particularly in Figs. 7, 8 and 9, a slide 33 is provided on the top flange of the left side plate l this slide being enclosed in and guided by a housing 34 secured to the said top flange. The slide 33 carries a depending lug 33 which projects through a slot in the top flange and is positioned at the front of the before-mentioned pin 30. A spring 35 serves to bias the slide 33 in the forward direction and movement of the slide is limited by a pin 36 which projects through a slot in the top Wall of the housing 34, A fingerpiece 31 projects laterally from the slide through a slot in the side of the housing 34.

With the barrel and barrel extension in their forward positions, as shown, the slide 33 upon being manually moved rearward by means of the fingerpiece 31, serves to move the pin 30 rearward thus moving the detent 28 rearward and withdrawing it from the notch 32. This frees the bar-- rel and permits it to be turned in the disengag ing direction. It will be observed that it is not necessary to hold the fingerpiece after the bar-- rel has started to turn. For the reasons already explained, the detent 28 will not enter the notch 32 when the parts come into register at the end of the first turn.

While the slide 33 and its depending lug 33 are adapted to normally move the pin 30 and the detent 28, they do not in any way interfere with the bodily rearward movement of the pin and detent during normal functioning f the gun.

What I claim is:

1. In an automatic firearm, the combination of a casing, a longitudinally reciprocable barrel, a barrel extension connected with the barrel and positioned within the casing, a breech block guided on the barrel extension for downward and upward movement out of and into breech-closing position, mechanism for moving the breech block downward and upward in timed relation with the reciprocation of the barrel and barrel extension, a relatively movable stop pivotally mounted on the barrel extension normally in position to limit downward movement of the breech block, and a spring-pressed detent for holding the stop in its normal operative position, the said detent being readily movable manually to enable the stop to move on its pivot out of its operative position and thus permit the breech block to move downward out of engagement with the barrel extension.

2. In an automatic firearm, the combination of a casing, a longitudinally reciprocable barrel, a barrel extension connected with the barrel and positioned within the casing, a breech block guided on the barrel extension for downward and upward movement out of and into breech-closing position, mechanism for moving the breech block downward and upward in timed relation with the reciprocation of the barrel and barrel extension, and a stop pivotally connected with the barrel extension and normally in position to limit downward movement of the breech block, the said stop being pivotally movable out of its operative position to permit the breech block to move downward out of engagement with the barrel extension.

3. In an automatic firearm, the combination of a casing, a longitudinally reciprocable barrel, a barrel extension connected with the barrel and positioned within the casing, a breech block guided on the barrel extension for downward and upward movement out of and into breech-closing position, mechanism for moving the breech block downward and upward in timed relation with the reciprocation of the barrel and barrel extension, 2. stop pivotally connected with the barrel extension for movement about a horizontal axis, the said stop being normally in position to limit downward movement of the breech block, and a means normally holding the stop in its operative position but manually movable to release the stop and enable it to move pivotally downward and thus permit the breech block to move downward out of engagement with the barrel extension.

4. In an automatic firearm, the combination of a casing, alongitudinally reciprocable barrel, a barrel extension connected with the barrelyand positioned within the casing, .a breech blockguided on the barrel extension for downward and upward movement out of vand into breech-closing position, mechanism including a longitudinally movable lock frame for moving the breech block downward and upward in timed relation with the reciprocation of the barrel and barrel extension, two transversely spaced reaction-spring devices connected with the lock frame, a yoke secured to the barrel extension for supporting the reactionspring devices, and a relatively movable stoppivoted at one end on the yoke normally in position to limit downward movement of the breech block by engagement of its other end with the-breech block, the said stop beingmovable out of its operative position to permit the breech block to move downward out of engagement with the barrel extension.

5. In an automatic firearm, the combination of a casing, a longitudinally reciprocable barrel, a barrel extension connectedwith the barrel and positioned wtihin the casing, the said extension having a depending lug, a recuperator having a threaded rod extending through a hole in the lug, a nut on the rod engaging the rear of the lug, said nut having a clearance cavity on its rear face disposable in a predetermined operative position, a breech block guided on the barrel extension immediately behind the lug for downward and upward movement out of and into breech-closing position, mechanism operable for moving the breech block downward and upward in timed relation with the reciprocation of the barrel and barrel extension, said clearance cavity accommodating a portion of the mechanism duringoperation when said nut is in said predetermined position, and a relatively movable stop carried by the barrel extension lug normally in position to barrel extension connected with the barrel positioned within the casing, the said extension having a depending lug, a recuperator having a threaded rod extending through a hole in the lug, a nut on the rod engaging the rear of the lug, a breech block guided on the barrel extension immediately behind the lug for downward and upward movement out of and into breech-closing position, mechanism for moving the breech block downward and upward in timed relation with the reciprocation of the barrel and barrel extension, a relatively movable stop carried by the barrel extension lug normally in position to limit downward movement of the breech block, the said stop when inposition to limit movement of the breech block engaging the said nut to prevent it from turning, and a spring-pressed detent normally entering a hole in the stop for holding it in its normal operative position, the said detent being prevented from entering the hole when the nut is out of normal position so as to prevent the stop from moving to its normal position.

GEORGE WEBB. 

